The manufacture of timepiece mainsprings is complex, and requires numerous steps, including a step of forming a ring and/or a step of press-rolling a portion of a wire, at one end of which an eye has previously been formed, to form the strip of the spring.
This press-rolling operation is complex, and requires perfect reproducibility. The spring is awkward to handle following the press-rolling operation.
CH Patent Application No 708674A2 in the name of Générale Ressort discloses an equipment for shaping a metal wire during a mainspring manufacturing method, comprising a system for driving the wire in two directions opposite to each other, and comprising a device for guiding and ejecting the wire; the equipment also includes a press-rolling device located in a first direction with reference to the drive system, an eye producing device located in the second, opposite direction, and a central wire-guide arranged on the drive system and intended to cooperate with at least one of the press-rolling and eye producing devices to deform the metal wire.
WO Patent Application No 2008/102388A1 in the name of Boldrini Spa discloses a roller press comprising a support structure carrying two rollers and a pressure roller which, in cooperation with each other, define a curved feed path for a plate to be bent. The rollers are movable relative to the pressure roller to vary at least one curvature value of the feed path. The apparatus further includes a pair of articulated kinematic mechanisms, each of which acts on a respective roller to move it along a plurality of paths located in a transverse plane to the axis of rotation of the roller.